522 
MR. F. GOTCH OX THE ELECTROMOTIVE PROPERTIES 
Circuit closed . • . 
. 5" 
to 15" 
after section 
+ 440 
55 
broken 
. 15" 
25" 
55 
55 
. . 
55 
closed . 
. 25" 
35" 
55 
55 
+ 230 
55 
broken 
. 35" 
45" 
55 
55 
, . 
55 
closed . 
. 45” 
55" 
55 
55 
+ 160 
55 
broken 
. 55" 
65" 
55 
55 
, . 
55 
closed . . 
. 65” 
75" 
55 
55 
+ 110 
55 
broken 
. 75" 
85" 
55 
55 
, . 
55 
closed . . . 
. 85" 
95" 
55 
55 
+ 65 
55 
broken 
. 95" 
105" 
55 
55 
• a 
55 
closed . . . 
. 105" 
115" 
55 
55 
+ 20 
The prolongation of the after-effect, or “ excitation remainder,” is most marked in 
this experiment. It will be noticed that it is always present when the response is 
such as to reach a great maximum of intensity, and this suggests the inquiry whether 
a similar change cannot be brought about by the passage through the tissue of an 
intense current of short duration. The experiments of du Bois-Reymond previously 
referred to show that such is the case. To this subject we now proceed. 
III. The Electromotive Changes following the Passage of Electrical Currents 
through the Organ. 
The term “ secondary” electromotive is applied by du Bois-Reymond (33) to the 
changes produced in excitable tissues by the passage through these of electrical currents. 
The work of du Bois-Reymond, followed by that of Hermann (34), Hering (35), 
and Biedermann (36), has shown that, in addition to the ordinary phenomena of 
electrolytic polarisation, there are special electromotive changes which are intimately 
connected with the vitality of the tissues experimented upon. The main fact may be 
broadly stated thus : the passage of a galvanic current of considerable intensity, and 
of short duration, through a tract of muscle or nerve, is followed not only by the 
electromotive changes accompanying ordinary polarisation, but by a prolonged electro¬ 
motive change which presents the characteristics of being the electrical index of a 
prolonged excitation. This is not, strictly speaking, the view which du Bois- 
Reymond took as to the nature of his discovery. According to the upholders of the 
molecular hypothesis, the passage of a galvanic current is followed by two sorts of 
polarisation—the ordinary negative polarisation, and a special positive polarisation, 
this last being an alteration in the condition of the vital electromotive molecules. It 
is simpler to call the latter effect an excitatory effect, and it will be thus designated 
here. The earlier work of du Bois-Reymond has been succeeded by the publication 
of the results of similar experiments carried out upon the electrical organ of the 
Torpedo (37), which show that here, too, the passage of an intense current of short 
duration is followed by electromotive changes of two kinds, those due to electrolytic 
polarisation, and special phenomena, due, probably, to excitation of the tissue. The 
